1. Field of the Invention
The invention relates to digital signal processing, and, in particular, to a data-encoding method known as low-density parity check (LDPC) coding.
2. Description of the Related Art
Communication is the transmission of information by a transmitter to a receiver over a communications channel. In the real world, the communications channel is a noisy channel, outputting to the receiver a distorted version of the information received from the transmitter. A hard disk (HD) drive is one such noisy channel, accepting information from a transmitter, storing that information, and then, possibly, transmitting a more or less distorted copy of that information to a receiver.
The distortion introduced by a communications channel such as an HD drive might be great enough to cause a channel error, i.e., where the receiver interprets the channel output signal as a 1 when the channel input signal was a 0, and vice versa. Channel errors reduce throughput, and are thus undesirable. Hence, there is an ongoing need for tools which detect and/or correct channel errors. Low-density parity check (LDPC) coding is one method for the detection and correction of channel errors. LDPC codes are among the known near-Shannon-limit codes that can achieve very low bit-error rates (BER) for low signal-to-noise ratio (SNR) applications. LDPC decoding is distinguished by its potential for parallelization, low implementation complexity, low decoding latency, as well as less-severe error-floors at high SNRs. LDPC codes are considered for virtually all the next-generation communication standards.